1. Technical Field
The present disclosure relates to a carbon canister as part of a fuel vapor management system on an automotive vehicle.
2. Background
For many years, carbon canisters containing activated carbon pellets have been used on automotive vehicles to reduce or prevent fuel vapors from a vehicle fuel tank escaping to atmosphere. In a typical application, the vapor storage canister is coupled to the vehicle fuel tank as well as the vehicle engine with a vent valve to atmosphere. The activated carbon pellets in the canister absorb fuel vapors from the fuel tank during a storage mode, such as when the fuel tank is being filled. The stored fuel vapors are periodically purged from the carbon pellets during a purge mode by passing air from atmosphere over the pellets to desorb the fuel, with the fuel vapor inducted by the engine and combusted during engine operation. The carbon pellets are added to the canister during assembly. Typically, a permanent filter, such as a foam filter, is installed at each entry/exit port to retain the pellets and any small particles that may break off of the pellets during assembly or subsequent operation. The size of each port is determined in conjunction with the filter characteristics to maintain a desired flow rate through the filter/port while accommodating some reduction in flow rate due to anticipated filter clogging. A decreased filter/port flow rate may result in incomplete purging of the stored fuel vapors during certain, regulated driving events. It is known in the prior art to provide a filter at each entry/exit port of the carbon canister to prevent the activated carbon pellets from migrating out of the carbon canister. It is also known in the prior art to affix tubes to the carbon canister housing to provide entry/exit ports. The resulting carbon canister is assembled of many parts. It is desirable to reduce the number of parts to be assembled to reduce cost and parts complexity and to increase robustness of the carbon canister.